Vol.2, No.3, 308-312 (2011)
doi:10.4236/as.2011.23041
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/AS/
Agricultural Scienc es
Uptake and distribution of 14C-labeled Fosthiazate in
tomato (Lycopersicon esculentum L.)
Santanu Mukherjee1, Surendra Kumar2, Anjana Srivastava1, Prakash Chandra Srivastava3*
1Department of Chemistry, College of Basic Science & Humanities, G.B. Pant Universi ty of Agricu lt ur e an d Technology, U.S. Na gar,
India;
2Radiations and Isot o p ic Tracers Lab o r a to ry, G.B. Pant University of Agriculture and Technology, U.S. Nagar, India;
3Department of Soil Science, G.B. Pant university of Agri c u lture & Technology, U.S. Nagar, India; *Correspo nding Author:
pcsriv@yahoo.com
Received 13 August 2010; revised 23 May 2011; accepted 21 July 2011.
ABSTRACT
The uptake of 14C-labeled fosthiazate (0.75 mg·L1)
by tomato plant s was studied in solution culture
both in the presence or absence of 2,4-dinitro-
phenol (DNP, 1 × 102 mM), a metabolic inhibitor.
Fosthiazate was rapidly taken up by tomato
plants and nearly one third of the finally ab-
sorbed quantity was taken up in the first half an
hour. The translocation of fosthiazate to the
shoot part was under metabolic control during
the initial stage of upt ake . The ki netics of up take
both in the presence and absence of DNP con-
formed well to the dual phase than a single
phase. In the presence of DNP, the uptake ca-
pacity (Vmax1) for the initial phase suffered, ap-
proximately three fold reduction occurred in
comparison to the absence of DNP while Vmax2
for the latter phase was statistically similar to
the value observed in the absence of DNP sig-
nifying the metabolic dependence of the initial
uptake phase. Autoradiography indicated that
fosthiazate in the tomato plants tends to accu-
mulate in the roots and at the root-shoot junc-
tion. In shoot, it is accumulated in the older
leaves especially, near the leaf tip an d margins.
Keywords: 14C-Fosthiazate; Uptake; Translocation;
Systemicity; Tomato
1. INTRODUCTION
Fosthiazate [(RS)-S-Sec-bentyle-O-ethyl 2 oxo 1,3-
thiazolidin-3-yl phosphonothioate)] is a relatively new
group non-fumigant, organophosphorus nematicide [1].
Studies in field plots have shown that fosthiazate exhib-
its similar efficacy as that other non-fumigant nemati-
cides against a wide range of plant parasite nematodes,
such as root knot nematode (Meloidogyne spp.), cyst
nematodes (Globodera spp.) and root lesion nematodes
(Pratylenchus spp.) [2]. It also has systemic activity
against various species of insects and mites on the foliar
part. Fosthiazate has been on the market in Japan since
1993 and is currently registered for use on potatoes for
controlling cyst nematodes in th e U.K. [3]. However, no
published data are currently available on the uptake and
translocation of 14C-fosthiazate in tomato. Therefore, the
present study was undertaken to study the uptake and
translocation of (14C) fosthiazate by intact tomato plants
and to examine the metabolic dependence of these proc-
esses.
2. MATERIALS AND METHODS
2.1. Chemicals
The fosthiazate chemical was procured from Shanghai
Institute of Chemical Industry Testing Centre, Shangh ai,
China. Radiolabelled 14C-fosthiazate compound was
procured from BRIT, Mumbai. All necessary chemicals
used in the investigation were procured from E. Merck,
Spectro Chem and Loba Chemicals, India
2.2. 14C Uptake & Distribution through
Solution Culture
Healthy seeds of tomato (var. Pant T-3) were sown in
three plastic trays (45 × 30 × 7.5 cm) filled with washed
quartz sand. After germination, 1/2 (half-strength) Hoag-
land solution was applied on alternate day for 2 weeks
and later the plants were thinned to maintain 30 plants
per tray. Thereafter, Hoagland solution of the full
strength was applied thrice in a week. When the plants
were 40 d old, plastic trays were filled with distilled wa-
ter and plants were gently removed from the trays to
ensure the minimum damage to the roots.
Exactly 150 ml Hoagland solution with or without
DNP (1 × 10–2 mM) were taken in conical flasks of 250
S. Mukherjee et al. / Agricultural Science 2 (2011) 308-312
Copyright © 2011 SciRes. Openly accessible at http://www.scirp.org/journal/AS/
309309
ml capacity. To each flask 0.5967 ci of 14C-fosthizate
was added except for the control (with no fosthiazate).
The final concentration of fosthiazate in the uptake solu-
tion was 0.75 mg/L. Two-40 d old-tomato plants were
placed in each flask ensuring that their roots were prop-
erly dipped in Hoagland solution. The flasks were im-
mediately tightly wrapped in black carbon paper to keep
roots under dark. Plants were kept under the fluorescent
light with the provision for aerating the solution. Plants
were removed from duplicate flasks at 0.5, 1.0, 2, 4, 6, 8,
12 and 24 h periods. After removal, plants were washed
in ice-cold tap water, Hoagland solution and distilled
water, respectively and soak-dried between blotting pa-
per sheets. One plant was kept for autoradiography and
another was separated in roots and shoot parts and
weighed on an electronic balance.
2.3. Solvent Extractant for Fosthiazate
The weighed root and shoot samples were weighed
and ground separately in the presence of 10 ml of
methanol: water (1:1) using a pestle and mortar. After
grinding, the sample was transferred to a conical flask
(100 ml capacity) using 20 ml methanol and extracted
for 1 h on a mechanical shaker. The contents were fil-
tered using Whatman No. 1 filter paper and 15 ml ex-
tract was passed through a column containing silica gel
(2 g), and 5 g Na2SO4 and leached. The leachate was
stored in glass vials.
2.4. Counting Procedure
One ml of leachate was taken in quartz glass scintilla-
tion vial and 9 ml of d ioxane based scin tillation cocktail
(10 g PPO, 0.25 g POPOP, 100 g naphthalene/L of di-
oxane) was added. Prior to counting each sample was
kept under dark for 10 h for the dark adaptation and to
prevent false counts [4]. Each sample was assayed for
the 14C- labeled fosthiazate activity on a liquid scintilla-
tion counter (Pacard-1600 TR) using the external stan-
dardization method.
2.5. Autoradiographic Techniques
Tomato plants after uptake study were kept in herbar-
ium sheets for drying. These plants were kept under the
X-ray film in the cassettes for 15 d exposure time. Then
negative films were subjected to positive method for
clear visualization of accumulation and translocation of
14C-labeled fos thiazate [5].
3. RESULTS AND DISCUSSION
The data on total amount of fosthiazate absorbed by
the whole plants of tomato at different time intervals
presented in Figure 1 indicated that fosthiazate was rap-
idly taken up by tomato plants and under normal condi-
tions nearly one third of the finally absorbed quantity
was taken up in the first half an hour. The accumulation
of fosthiazate in the tomato plants continued till the last
observation (24 h).
The presence of 2,4-dinitrophenol ( DNP), a metabolic
inhibitor decreased the uptake of fosthiazate by tomato
plants at all time intervals. The values of percent inhibi-
tion in the presence of DNP indicated that the relative
inhibition was initially higher up to 2 h (44.68% to
59.66%) as compared to the later timings.Numerous
investigations showed that carprop amid, a fungicide was
rapidly absorbed and translocated by 14 d old rice seed-
lings in half an hour uptake period [6].
Figure 1. Total uptake of fosthiazate by tomato plants (ug·plant–1)
without or with 2,4-dintrophenol. The numerical values above the his-
tograms indicate percent inhibition in the presence of DNP.
S. Mukherjee et al. / Agricultural Science 2 (2011) 308-312
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310
The data on percent distribution of absorbed fosthi-
azate in roots and shoot of tomato plants both with or
without DNP are depicted in Figure 2. Under normal
conditions (without DNP), the absorbed fosthiazate was
easily translocated to the shoot part. However, in the
presence of DNP most of the absorbed fosthiazate was
retained in the roots during the initial stages of uptake
and its translocation to shoo t part was slowed down.
The distributions of radiolabelled fosthiazate in to-
mato roots (at 0.5 h) and in an intact tomato shoot (at 4 h)
are depicted in an autoradiograph (Plate 1). As shown in
the autoradiographs, the absorbed fosthiazate mainly ac-
cumulated in the roots and also at the root-shoot junction.
The retention of fosthiazate in the stem was much lesser
as compared to the leaves. In the shoot, the lower older
leaves accumulated more fosthiazate as compared to the
younger upper leaves. Within the leaf, fosthiazate con-
centrated at the leaf tip and also at leaf margins. The
translocation of fosthiazate appeared to be mediated by
the apoplastic movement which is solely regulated by
physical forces like the transpirational pull and root
pressure and leads to the accumulation of the compound
at the apex and margins of leaves [7-9]. However, the
observed partial inhibition of fosthiazate accumulation in
the shoot in the presence of a metabolic inhibitor like
DNP indicated that the translocation of absorbed fosthi-
azate to the shoot was partly dependent on the metabo-
lism.
Plate 1. Radioautographs of 14C-fosthiazate exposed tomato
roots (A, after 0.5 h) and whole plant (B, after 24 h).
Time dependent kinetics of fosthiazate uptake by to-
mato plants both in the presence and absence of DNP
was examined by using a modified Langmuir type equa-
tion (Equatio n 1).
max max
11 .
B
qVV t
 1
(1)
where,
q = amount of 14C fosthiazate taken up by plant at
time ‘t’;
Vmax = ma ximum absorption of 14 C fosthiazate/ plant;
B = a constant;
T = time (h).
The uptake data of fosthiazate by tomato plants were
fitted to the Equation 1 by plotting the reciprocals of
Figure 2. Percent distribution of fosthiazate between roots and shoot under both without and with DNP.
S. Mukherjee et al. / Agricultural Science 2 (2011) 308-312
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311311
amount of fosthiazate (µg·plant–1) absorbed by plants at
a given time against time (h) (Figure 3). Assuming that
the kinetics of fosthiazate was governed by a single
phase, the values of Vmax, B and the coefficients of de-
termination (R2) for single phase were computed. How-
ever, a close perusal of the distribution of the points in
Figure 3 revealed that the uptake kinetics could be
splitted into two distinct straight line parts; the first
phase up to 2 h and the second one which appeared to
operate beyond 2 h onward upto 24 h. The data of both
the phases were fitted individually to the Equation 1.
The computed values of Vmax, B and R2 for both the
single and dual phases for tomato plant are presented in
Tabl e 1. Statistically sig nificant values of R2-value indi-
cated that the uptake data conformed to the kinetic equa-
tion used in the study. A comparison to R2-values for the
single and dual uptake phases revealed that the dual
phase could account the uptake pattern of fosthiazate by
tomato plants better than single phase both in the pres-
ence and the absence of DNP. In the presence of DNP,
the value of Vmax for the initial phase suffered a signifi-
cant drastic (roughly three fold) reduction in comparison
to the absence of DNP. On the other hand, the value of
Vmax for the latter phase in the presence of DNP was sta-
tistically similar to the value observed in the absence of
DNP. This clearly indicated that the initial uptake of
fosthiazate by tomato plants was under metabolic con-
trol.
In conclusion, this study showed that uptake of fost-
hiazate, a nematicide, by tomato plants was quite rapid
Table 1. Kinetic parameters of single and dual phase uptake of
fosthiazate by roots and shoots of tomato plants with and
without 2,4-dinitrophenol (DNP).
Model Parameters Without DNP With DNP
Vmax 2.786 1.544
B 0.931 1.050
Single phase
R2 0.949** 0.751*
Vmax1 2.214 0.749
B1 0.598 1.680 Dual phase (I)
R12 0.999** 0.991*
Vmax2 3.731 3.3934
B2 3.323 11.565 Dual phase (II)
R22 0.926 0.994
**significant at p = 0.01 and *significant at p = 0.05.
suiting to its application through irrigation water. The
kinetics of uptake both in the presence or absence of
DNP conformed well to the dual phase than a single
phase. The initial phase of uptake was under metabolic
control. The initial translocation of fosthiazate to the
shoot part was inhibited by metabolic inhibitor. In the
tomato plants, fosthiazate tends to accumulate more in
the roots and at the root-shoot junction. In shoot, it is
accumulated in the older leaves especially, near the leaf
tip and margins.
4. ACKNOWLEDGEMENT
The authors are highly indebted to university authority for providing
Figure 3. A plot of 1/q versus 1/t single and dual phase uptake of Fosthiazate by whole tomato plant. **Signifi-
cant at p = 0.01, *Significan t a t p = 0.05.
S. Mukherjee et al. / Agricultural Science 2 (2011) 308-312
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312
necessary facilities.
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